An electronic ballast circuit for energizing gas discharge lamps is comprised of a rectifier for converting low frequency, alternating current ("AC") power to direct current ("DC") power; a boost for increasing the voltage of the DC power, and an inverter (commonly a half-bridge) to convert the DC power to AC power at a very high frequency (on the order of 24 kilohertz ("KHz")).
This type of circuit attains a high power factor and a low total harmonic distortion (THD), and is capable of being dimmed.
However, such a circuit requires three transistors and numerous other components. The topology is hard to manufacture as a low cost integrated circuit. The result is a ballast that is relatively expensive when compared with magnetic ballasts.
Attempts have been made to reduce the number of components. However, reduction of the number of components has heretofore either necessitated expensive high voltage integrated circuits ("ICs") or else has sacrificed power factor, THD and dimming capability.
A circuit which could be manufactured with few components using conventional low cost ICs and yet maintains a high power factor low THD and dimming capability is thus desireable.